I'm trying to redesign my west-facing border as over the years it has become "bitty" - mainly due to my habit of propagating plants and then just stuffing them in there (till I decide where they can go) and of course some plants at the front are now taller than the ones at the back as a result. I have started by making a list of all the shrubs, trees and plants there and sorting them by height and spread on paper but not sure where to proceed next...

My garden is informal and cottagey type planting. The border measures 8m wide by 3m deep and is fenced at the back.